This book explores the innovative application of biowaste-derived green nanomaterials for sustainable wastewater remediation. It highlights cost-effective strategies, such as adsorption, photocatalysis, and hybrid approaches, for the remediation of pollutants, including heavy metals, dyes, pharmaceuticals, pesticides, and microplastics, using biowaste-fabricated green nanomaterials, while emphasizing regeneration, reusability, ecological safety, legal aspects, and life cycle assessment. Bridging fundamental science with real-world sustainable water remediation applications, book serves as a comprehensive resource for researchers, graduate students, and environmental engineers, as well as a practical guide for industry experts, NGOs, and sustainability professionals. Aligning cutting-edge green nanotechnology-based nanomaterials with the United Nations' Sustainable Development Goals (SDGs) underscores both scientific innovation and global impact, offering a roadmap toward cleaner water and a more sustainable future.